Endocrine Abstracts

Iodine is an essential part of thyroid hormones, and many processes in the thyroid gland adapt to changes in iodine supply. Still, abnormalities in iodine intake are of major importance for the occurrence of thyroid diseases. Historically, the intake of iodine from food and beverage has been low in large parts of the world. Depending on the level of insufficiency, this has been associated with disturbed reproduction, developmental brain damage, and a high occurrence of goitre and thyroid function abnormalities in the populations involved.

In recent decades national committees and international organizations (ICCIDD, WHO, UNICEF) have succeeded in improving iodine nutrition in many countries by iodine fortification of salt. In other countries, people have experienced a more haphazard increase in iodine intake caused by farmers’ use of iodine rich cattle feed, or by food producers’ addition of iodine containing chemicals to food.

The experience with this development is that focus on iodine intake in a population is necessary to avoid relapse of iodine deficiency, but focus is also necessary to avoid excessive iodine intake in the population or in subpopulations. Iodine has many effects on the thyroid gland, and both high and low iodine supply may lead to abnormalities.

Iodine requirements are considerably higher during pregnancy and lactation, and the developing brain is particularly sensitive to abnormalities in thyroid function. Therefore, special focus are needed on iodine intake and thyroid function in pregnant women.

Iodine intake of a population should be monitored and, if necessary, adjusted by universal or focused intervention. Non-regulated and non-declared use of iodine containing substances in dairy farming, food industry and cosmetics is probably best avoided.